The present disclosure generally relates to the methods for enhanced processing of cellulosic biomass and other forms of biomass using flash dessication and/or mechanical hydrodynamic cavitation.
Over the past thirty years, significant attention has been given to the production of ethyl alcohol, or “ethanol,” for use as an alternative fuel. Ethanol not only burns cleaner than fossil fuels, but also can be produced using renewable sources such as corn, corn stover, corn cobs, switch grass forestry products, and the like.
Ethanol can be produced from various grains such as corn by either a wet milling or a dry mill process. In the wet milling process, the corn kernel is separated into different components such as germ, starch, protein, and fiber, resulting in several co-products. For example, separated germ is further processed for fat recovery; starch is saccharified and fermented for ethanol production; and protein and fiber can be used as feed material. In a traditional dry mill process, the corn is not fractionated and only two co-products are generally produced in addition to ethanol, Distillers Grains and CO2. In this process, corn is ground and processed through fermentation and distillation, where the end products are ethanol, whole stillage and CO2. The whole stillage contains water, a portion of starch that was not fermented, and the remaining non-fermentable portions of the kernel of corn such as protein, fiber, cellulose and hemicellulose corn fat and ash. Water is then removed from the whole stillage to form the dried distillers grains. At present, an estimated one hundred and fifty “dry milling” plants are producing over six billion gallons of ethanol per year. Additional plants presently idle or under construction are expected to add more than three billion gallons to this total.
While most of the ethanol production facilities currently in use are considered “dry milling”, there has been a recent movement to build “fractionation-based” dry milling ethanol production facilities. These fractionated facilities attempt to separate as much of the non-fermentable portions of the grain as practical prior to the fermentation step. For example, corn kernels are comprised of three primary components: endosperm, germ, and bran. The endosperm contains the majority of the starch within the kernel of corn, or about 85%, whereas the germ and the bran contain high concentrations of non-fermentables (fiber, protein, and corn fat). Wet and dry fractionation technologies exist today that can be integrated into the dry milling process to effectively separate the endosperm, germ, and bran with minimal losses. The separated endosperm can then be conveyed to the fermentation process, and the germ and bran can then be sold directly to other markets and/or further processed.
With less non-fermentable mass entering the ethanol dry milling production process, greater volumes of ethanol can be produced per volume of fermentation capacity. In addition, separating non-fermentables prior to fermentation allows for a reduced mass of whole stillage exiting distillation and advantageously reduces energy loads on the whole stillage dehydration equipment. The downside of current technology is that the separation equipment and processes used need improvements to make the processes economically viable. For example, some of the starch exits with the non-fermentable components, thereby increasing the mass of corn required per volume of ethanol produced.
In both traditional dry milling and fractionated dry milling corn ethanol production facilities, the whole stillage is typically dehydrated by separating the heavy phase from the lighter phase using a centrifuge. The heavier phase is referred to as wet distillers grains and the lighter phase is referred to as thin stillage. The thin stillage is concentrated efficiently using multi-effect evaporation to produce a product referred to as condensed distillers solubles. Fat recovery methods are currently available to extract oil from the resulting co-products.
As the majority of United States derived biofuels are produced from grain, there needs to be continued focus to integrate new technologies that allow for more efficient conversion of grain to ethanol to allow for increased output relative to the same mass of grain inputs.
While the majority of ethanol produced in the United States is from grain, particularly corn, there remains a need to produce ethanol from alternative cellulosic feedstocks to offset the need for the various grains while allowing reduced dependence on petroleum based fuels. Desirable alternative feedstocks include, without limitation, corn cob, corn stover, DDGS (Distillers Dried Grain with Solubles), bran from fractionated production facilities, and many other forms of cellulosic biomass or cellulose containing waste streams such as paper, trash and/or sewage sludge.